The proposed project embraces the following aims: (1) To gain a general understanding of the biochemical and genetic mechanisms controlling the synthesis, repair and recombination of DNA. (2) To establish the function of genes that are essential for the continuation of DNA replication after it is intiated. (3) To elucidate the role of phage and host functions in the mechanism by which the monomer DNA of early T4 replicative stage is converted into concatemar DNA of the late replicative stage. (4) To comparatively study the control of deoxyribonucleotide biosynthesis in normal mammalian cells and their chemical transformed counterparts.